SPRAY SOLUTION pHBy Dr. Claudio Pasian According to Dr. Raymond Cloyd, University of Illinois, it is very important to double check a spray solution's pH before application. Spray solutions for most pesticides should have a pH close to neutral (pH = 7). If the pH is higher, it may reduce the efficacy (or the ability to do its job) of the product. Some products become phytotoxic if the spray solution pH is too low. As a result, water quality is important (e.g. pH and alkalinity). For this reason, researchers testing efficacy of new products always use distilled water. Always read the label for any specific information regarding the pH of the spray solution. Many growers are aware of this danger but are reluctant to use their pH meters because they wonder if the pesticide solution will ruin their pH meter's electrode. Currently, information regarding the effect of a chemical solution on the pH meter electrode is not available but if enough growers request it, manufacturers would probably respond with an answer. In the meantime, growers can test using pH testing strips. Spraying represents a cost in materials and application time. As a result, it is important to make each chemical application as succesful as possible. It is important for growers to know how the pH of the spray solution affects the chemicals' efficacy. Rick Yates , Technical Support Manager at the Griffin Grennhouse and Nursery Supplies, Inc. , has sent us a chart they have assembled with optimal pH ranges of spraying solution of fungicides, insecticides, plant growth regulators and herbicides. They did not do any research on this subject, rather, they reported the answers received from the companies that they questioned. Following, are tables with pH ranges: Rick has also sent us information about a product they sell called pHase5. This new product is a buffer and has a color indicator. Growers can add this product into the water until it reaches the color that indicates a given pH. For example, 5 = pink or red; 6 = orange; etc. Not all pesticides react the same to the pH of the spray water solution. Some products should not be used with pHase5:
For more information, please read the label of pHase5 |
